This application is based on Patent Application No. 2000-240259 filed Aug. 8, 2000 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to a card edge connector into which a card type circuit board having a plurality of contact pads at its end portion is inserted.
2. Description of the Related Art
A card edge connector electrically connects a card type circuit board which is of a printed circuit board having an array of conductive contact pads on one or both surfaces of its end portion to a printed circuit board of a variety of kinds of electronic devices.
The card edge connector of this kind normally has a rectangular parallelepiped housing with a slot through which the card type circuit board is inserted into the housing, and a plurality of elastic contacts arrayed on one or both sides of the slot.
In case that a double-faced card type circuit board having contact pads arrayed on its both surfaces is inserted into a double-faced card edge connector, which is one type of the above-described card edge connector, on condition that the card type circuit board is supplied with electricity from a mother board on which the connector is mounted or from a cable connected to the connector, contact pads on one surface of the card type circuit board are applied with positive voltage and contact pads on the other surface with negative voltage.
The contact that electrically connects to the contact pad is made from a leaf spring material and has a connecting portion connected to the mother board or cable, a fixed portion fixed in the connector housing, a spring portion and a contact portion.
In the conventional card edge connector, each contact is provided with one contact portion to connect with a corresponding one of the contact pads of the card type circuit board, so that when large electric power is supplied to the card type circuit board, the large current flows through the contacting portion between the contact and the contact pad, raising the temperatures of all portions of the contact, i.e., a contact portion, a spring portion, a fixed portion and a connecting portion. The conventional card edge connector therefore has a problem of a temperature rise in excess of a predetermined allowable temperature range.
The present invention has been accomplished under these circumstances and its objective is to provide a card edge connector that can prevent an excess of temperature rise in the contacts even when large electric power is fed.
In the first aspect of the present invention, there is provided a card edge connector electrically connecting to a card type circuit board, wherein the card type circuit board has a plurality of contact pads arrayed on at least one of surfaces of an edge portion thereof, the card edge connector comprising:
a housing having a slot into which the card type circuit board is inserted; and
a plurality of contacts, each comprising a plurality of stacked contact pieces, each of the stacked contact pieces having a fixed portion to be fixed in the housing, a connecting portion extending from the fixed portion in one direction, a spring portion extending from the fixed portion in the other direction and being elastically displaceable, and a contact portion at a free end of the spring portion;
wherein the contact portions of the plurality of contact pieces are allocated in the direction of the length of the contact within a size of the corresponding contact pad.
Here, the fixed portion, the spring portion and the contact portion of each of the stacked contact pieces may be almost equal in width.
The spring portion and the contact portion of each of the stacked contact pieces may be divided into a plurality of parts in the direction of the width of the contact.
The connecting portions of the plurality of contact pieces may be shifted in the direction of the width of the contact so that the connecting portions do not overlap.
The fixed portions of the plurality of stacked contact pieces may be press-fitted and securely held in each of grooves formed in the housing.
In the second aspect of the present invention, there is provided a card edge connector electrically connecting to a card type circuit board, wherein the card type circuit board has a plurality of contact pads arrayed on at least one of surfaces of an edge portion thereof, the card edge connector comprising:
a housing having a slot for accommodating the card type circuit board is inserted; and
a plurality of contacts, each of contacts having a fixed portion to be fixed in the housing, a connecting portion extending from the fixed portion in one direction, a plurality of spring portions extending from the fixed portion in the other direction and being elastically displaceable, and contact portions provided one at a free end of each of the plurality of spring portions;
wherein the contact portions are allocated in the directions of the width and the length of the contact within a size of the corresponding contact pad.
In this invention, the spring portion of each of the stacked contact pieces is divided into a plurality of spring portions so that the contact portions of the contact can be allocated dispersedly in the directions of the width and the length of the contact. This arrangement can increase the number of contact portions to engage the corresponding contact pad, reduce contact resistance and minimize a temperature rise.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.